The feature is very rudimentary [1], and causes problems when not using
bundled deps, where it might then fail to find `busted.runner` due to
this.
E.g. with "-DUSE_BUNDLED=OFF -DUSE_BUNDLED_LUAROCKS=ON":
`.deps/usr/bin/busted` contains `exec '/usr/bin/luajit' -e …`, i.e. it
run luajit with adjusted lpath etc.
But using `--lua /usr/bin/luajit` then causes this `busted` wrapper to
be replaced with just `/usr/bin/luajit`, i.e. it is missing the adjusted
lpath then.
1: 9eb6c9cf93
93297cfc6f